CAIRO - The Islamist militant group Ansar Bayt al-Maqdis said on Tuesday the bombing of a tourist bus in Egypt's Sinai that killed two South Koreans and the Egyptian driver on Sunday was a suicide attack carried out by one of its fighters, and threatened more strikes against economic targets.

The attack on the bus, which was traveling to Israel from St. Catherine's Monastery, a popular tourist destination in the south Sinai, was the first assault on tourists since President Mohamed Morsi's ouster spurred an Islamist insurgency.

"Ansar Bayt al-Maqdis has successfully sacrificed one of its heroes to detonate the bus headed toward the Zionists, and this comes as part of our economic war against this regime of traitors," the group said in a statement.